Site Statistics

What is the relationship between string net theory and string / M-theory?

+ 7 like- 0 dislike

58 views

I've just learned from this one of Prof. Wen's answers that there exists a theory called string net theory. Since I've never heard about this before it picks my curiosity, so I`d like to ask some questions:

How is string net theory related to the "usual" string /-M-theory framework? I mean if there is a relationship between them ...

Are the strings in string net theory and in string / M-theory the same?

What are the differences in the goals one wants to achieve or phenomena in nature one can describe with those two theories?

Your comment on this question:

To answer, leave an answer instead. Comments are usually for non-answers.
To mask links under text, please type your text, highlight it, and click the "link" button. You can then enter your link URL.
To alert a user, please use the "@" command and remove spaces from the username, example, the user "John Doe" should be pinged as "@JohnDoe", while the user "Johndoe" should be pinged as "@Johndoe". The post author is always automatically pinged (unless you are the post author).
Please consult the FAQ for as to how to format your post.

Live preview (may slow down editor)Preview

Live Preview

Preview

Your name to display (optional):

Email me at this address if a comment is added after mine:Email me if a comment is added after mine

Privacy: Your email address will only be used for sending these notifications.

1 Answer

We know that superstring theory is a potential theory of everything. One may want to ask what is the difference between the string-net-liquid approach and the superstring approach?

Our understanding of the superstring theory has been evolving. According to an early understanding of the superstring theory, all the elementary particles correspond to small segments of superstrings. Different vibration modes of a small superstring result in different types of elementary particles.

The above point of view is very different from that of the string-net liquid. According to the string-net picture, everything comes from simple qubits that form the space. The qubits fill the whole space, and the qubits are the space. No qubits no space. The string-nets are fromed by the "1" qubits. The strings can be as long as the size of universe. Light (photons) correspond to the collective motion of the string-nets that fill the space and an electron corresponds to a single end of string. (See a picture of string-net "vaccum". See also a talk)

A modern understanding of the superstring theory is still under development. According to Witten, one of the most important questions in superstring theory is to understand what is superstring. So at this time, it is impossible to compare the modern understanding of the superstring theory with the string-net theory. In particular it not clear if the superstring theory can be viewed as a local bosonic system (ie a qubit system). The string-net theory is fundamentally a local bosonic system (ie a qubit system).

So, if superstring theory is a qubit model (or a quantum spin model in condensed matter physics), then superstring theory and the string-net theory is the same, since the string-net theory is a qubit model (or a quantum spin model in condensed matter physics).

Thanks for these nice explanations, it already helps. Before I`ll gonna watch the slides of the talk, there are some further things I`m not sure if I get it right: conserning the qubits of value 1 that make up space, are they some kind of excitations of the spin net too? When you say photons are excitations of collective motions of the string net (?), is this true for all of the bosons in the theory? The part with the electrons (and other fermions too?) that correspond to a single end of a string I dont understand yet. Are they attached at the ends

...(similar as the querks in the string model for meson scattering) or do the electrons (and other fermions) correspond to the motion of just the respective endpoint? BTW is string net theory supersymmetric too and what number of spacetime dimensions is needed to formulate it consistently? Ok, now I better gonna watch the slides :-)

The space is made of qubits of value 1 or 0. The string is formed by qubits of value 1. The ground state is a superposition of all string-net configurations, which is particular quantum entangled state of qubits. The collective excitation of this particular entangled many-qubit state happen to be light. The end of string correspond to a topological excitations above the ground state which correspond to electrons. Any gauge charged particle correspond to string ends, bosons or fermions. String-net does not have to be supersymmetric, and lives in any dimensions.

Your comment on this answer:

To answer, leave an answer instead. Comments are usually for non-answers.
To mask links under text, please type your text, highlight it, and click the "link" button. You can then enter your link URL.
To alert a user, please use the "@" command and remove spaces from the username, example, the user "John Doe" should be pinged as "@JohnDoe", while the user "Johndoe" should be pinged as "@Johndoe". The post author is always automatically pinged (unless you are the post author).
Please consult the FAQ for as to how to format your post.

Live preview (may slow down editor)Preview

Live Preview

Preview

Your name to display (optional):

Email me at this address if a comment is added after mine:Email me if a comment is added after mine

Privacy: Your email address will only be used for sending these notifications.

Your answer

Please use answers only to (at least partly) answer questions. To comment, discuss, or ask for clarification, leave a comment instead.
To mask links under text, please type your text, highlight it, and click the "link" button. You can then enter your link URL.
Please consult the FAQ for as to how to format your post.
This is the answer box; if you want to write a comment instead, please use the 'add comment' button.

Live preview (may slow down editor)Preview

Live Preview

Preview

Your name to display (optional):

Email me at this address if my answer is selected or commented on:Email me if my answer is selected or commented on

Privacy: Your email address will only be used for sending these notifications.

Anti-spam verification:

If you are a human please identify the position of the character covered by the symbol $\varnothing$ in the following word:p$\hbar\varnothing$sicsOverflowThen drag the red bullet below over the corresponding character of our banner. When you drop it there, the bullet changes to green (on slow internet connections after a few seconds).